Lambda Sensor Preheating Control via Duty Ratio Correction
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Solution Overview
Problem
Existing lambda oxygen sensor preheating control methods fail to ensure a consistent effective voltage, leading to potential shortages or excesses in preheating, which can adversely affect the sensor's lifetime.
Innovation Solution
A lambda oxygen sensor preheating control method and device that applies a pulse voltage using PWM control, with a correction to the duty ratio of the pulse voltage based on a predetermined arithmetic expression to compensate for delays in the rise and fall times, ensuring a reliable and stable preheating process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a pulse voltage is applied to the heater using PWM control with a predetermined duty ratio, then the preheating control can be simplified and implemented, but the effective voltage applied to the heater decreases due to rise time and fall time delays, causing preheating shortage
Solution Approach 1:
The patent changes the duty ratio parameter of the PWM signal to compensate for the effective voltage loss. By calculating the corrected duty ratio that accounts for rise time and fall time delays, the system maintains the intended effective voltage applied to the heater, thereby ensuring reliable preheating control without modifying the PWM control mechanism itself
Solution Approach 2:
The patent introduces a feedback mechanism where the actual effective voltage (or equivalent heating effect) is monitored and used to adjust the duty ratio. The correction value is determined based on the difference between the intended and actual heating效果, creating a closed-loop control that compensates for the rise/fall time delays
2Device complexity
If the preheating control is performed without ensuring sufficient effective voltage, then the control process can be simplified, but the lambda oxygen sensor may suffer from preheating shortage which adversely affects its lifetime
Solution Approach 1:
The patent applies preliminary action by pre-calculating the corrected duty ratio before applying the PWM signal to the heater. The correction value is determined in advance based on the relationship between duty ratio and effective voltage, ensuring that the heater receives the correct effective voltage from the start of preheating, thereby protecting the sensor lifetime without adding complex real-time adjustments
3Reliability
If the pulse voltage duty ratio is increased to compensate for effective voltage loss, then the effective voltage can be maintained, but the preheating may become excessive which also adversely affects the sensor lifetime
Solution Approach 1:
The patent uses feedback control to precisely adjust the duty ratio correction value. By monitoring the actual heating effect and comparing it with the target value, the system determines the appropriate correction amount, avoiding both insufficient and excessive preheating. This closed-loop approach ensures the sensor receives exactly the required effective voltage, extending its lifetime
Solution Approach 2:
The patent makes precise parameter adjustments to the duty ratio based on calculated correction values. Rather than using a fixed large correction, the system dynamically adjusts the duty ratio parameter according to the actual effective voltage requirement, preventing over-preheating while maintaining reliable voltage levels
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for precise control of the effective voltage applied to the heater, preventing preheating shortages or excesses and thereby extending the lifetime of the lambda oxygen sensor while maintaining reliable operation.
Implementation Method 1
it is necessary to perform a preheating control of a heater before performing an operation of detecting the concentration of oxygen
Data Source
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AI summary
A desired effective voltage can be ensured with certainty in a preheating control. An operation control part 52 reads a correction value c with respect to a battery voltage Vb at the time of performing correction based on preliminarily stored correlation between a battery voltage Vb of a vehicle-use battery and a correction value c (S104, S106), and compensates for lowering of an effective value of a pulse voltage by adding a correction value c to a duty ratio calculated by a predetermined arithmetic expression thus ensuring a desired effective voltage with certainty in a preheating control.